Flexible perovskite solar cells (f‐PSCs) have attracted great attention due to their promising commercial prospects. However, the performance of f‐PSCs is generally worse than that of their rigid counterparts. Herein, it is found that the unsatisfactory performance of planar heterojunction (PHJ) f‐PSCs can be attributed to the undesirable morphology of electron transport layer (ETL), which results from the rough surface of the flexible substrate. Precise control over the thickness and morphology of ETL tin dioxide (SnO2) not only reduces the reflectance of the indium tin oxide (ITO) on polyethylene 2,6‐naphthalate (PEN) substrate and enhances photon collection, but also decreases the trap‐state densities of perovskite films and the charge transfer resistance, leading to a great enhancement of device performance. Consequently, the f‐PSCs, with a structure of PEN/ITO/SnO2/perovskite/Spiro‐OMeTAD/Ag, exhibit a power conversion efficiency (PCE) up to 19.51% and a steady output of 19.01%. Furthermore, the f‐PSCs show a robust bending resistance and maintain about 95% of initial PCE after 6000 bending cycles at a bending radius of 8 mm, and they present an outstanding long‐term stability and retain about 90% of the initial performance after >1000 h storage in air (10% relative humidity) without encapsulation.

Perovskite cesium lead halide (CsPbBr3) has attracted considerable attention due to its excellent optoelectronic properties and superior stability against moisture, oxygen, light, and heat.

Inorganic perovskite cesium lead halide (CsPbBr3) has attracted considerable attention because of its particularly excellent optoelectronics properties and high stability in humidity environments. Here, highly crystalline CsPbBr3 films with different morphologies and grain sizes were prepared via a one-step low pressure chemical vapor deposition (CVD). The structure-activity relationship between film microstructure and photodetectors (PDs) performance are investigated. The CsPbBr3 PD prepared at ∼190 °C possess an excellent response in the UV–Vis region and exhibits a fast response time of 0.7 ms/1.0 ms. Under 405 nm laser irradiation, the PD has a high responsivity, detectivity, external quantum efficiency, and switch ratio of 3.49 A W−1, 1.50 × 1013 Jones, 1075.4%, and 3.29 × 105, respectively. More importantly, the PD maintains 93% of original photocurrent when exposed to air for 28 d, which demonstrates excellent stability. At the same time, the CsPbBr3 films prepared via CVD are not dependent on the substrate, and the PDs exhibit similar performance on glass, SiO2/Si and polyimide substrates. The photocurrent of the flexible PD is maintained at 86% of the initial device performance parameters after 1000 bending cycles. These results indicate that the CsPbBr3 perovskite films prepared via CVD have great potential for application in high-performance, stable and flexible PDs.

Organic–inorganic hybrid perovskites are considered as a class of star materials for optoelectronic devices. However, the stability is one of the big issues. Herein, an MAPbI3 perovskite film with high stability is fabricated using chemical vapor deposition (CVD). The stability and performance of the MAPbI3 photodetector are further improved by constructing an MAPbI3 heterojunction with the organic semiconductor C8BTBT. The MAPbI3/C8BTBT heterojunction photodetector shows a wide spectral response range from ultraviolet to visible light and a fast response time of 30 ms/12 ms. Under laser irradiation at 405 nm, the responsivity of the MAPbI3/C8BTBT heterojunction photodetector reaches 6.09 A W−1, which is an 11.9‐fold improvement as compared with the MAPbI3 photodetector (0.51 A W−1). After storage under ambient conditions (humidity of ≈35%) for 2 months, the MAPbI3/C8BTBT heterojunction photodetector still exhibits excellent stability and the photocurrent maintains 93.7% of its initially measured value. The excellent stability under ambient conditions is likely the result of the stable MAPbI3 film that is fabricated via CVD and the protection of the organic semiconductor layer C8BTBT. The results provide a feasible route toward high‐performance and stable perovskite optoelectronic devices by combining CVD with perovskite heterojunctions.